1. Field of the Invention
The present invention relates generally to circuit breakers incorporated in switchgears such as control centers, and more particularly to a handle operating mechanism for operating an operation handle of the circuit breaker of the switchgear.
2. Description of the Prior Art
In the above-described handle operating mechanism of the circuit breaker incorporated in the switchgear, a knob of the handle is prevented from being moved when a compartment door of the switchgear is opened with the circuit breaker electrically opened by operating the handle knob, thereby preventing the circuit breaker from being electrically closed. When closed, the compartment door of the switchgear is locked to its closed position and the knob is allowed to be operated so that the circuit breaker may be electrically closed.
Japanese Utility Model Laid-open Application No. 599458 discloses such a handle operating mechanism, which is shown in FIG. 7. Referring to FIG. 7, an engagement member 3 is rotatably mounted on the backside wall of a frame 1 with a support shaft 2 interposed therebetween. A cam plate 5 is rotatably moved together with a handle knob 4 mounted on the front wall of the frame 1. When a circuit breaker (not shown) is electrically opened with the compartment door of the switchgear opened, a claw 3a of the engagement member 3 is caused to engage with an engagement portion 5a of the cam plate 5, as is shown by the solid line in FIG. 7, thereby preventing the cam plate 5 from being rotatably moved to its circuit breaker closing position as shown by the arrow A. Consequently, an actuating member 6 rotatably moved together with the cam plate 5 may be prevented from being rotatably moved, whereby the operation handle inserted in a bow-shaped aperture 6a of the actuating member 6 beforehand is not allowed to be moved from its OFF position to its ON position. Whereas, when the compartment door is closed, a projection 3b of the engagement member 3 is engaged with an engagement claw 7a provided at the distal end of an interlocking arm 7 extending from the backside of the compartment door, as shown by the alternate long and two short dashes line in FIG. 7. When the projection 3b is engaged with the engagement claw 7a, the engagement member 3 is rotatably moved in the direction of the arrow B against spring force of a torsion coil spring 9 attached to a support shaft 8 of the actuating member 6, thereby disengaging the claw 3a from the engagement portion 5a of the cam plate 5. The cam plate 5 is thus allowed to be rotatably moved in the direction of the arrow A and accordingly, the circuit breaker may be electrically closed.
As described above, the prior handle operating mechanism comprises independent mechanical parts, that is, the frame 1, operation knob 2, engagement member 3, and a transmission mechanism for transmitting movement of the operation knob 2 to the handle of the circuit breaker, which mechanism comprising independent parts such as the cam plate 5 and the actuating member 6. The prior handle operating mechanism thus has a disadvantage that a large number of parts to be assembled are required. Consequently, the assembly work of the circuit breakers requires much labor, resulting in high production cost.